Making lithium metal - seawater battery cells having protected lithium electrodes

ABSTRACT

Active metal and active metal intercalation electrode structures and battery cells having ionically conductive protective architecture including an active metal (e.g., lithium) conductive impervious layer separated from the electrode (anode) by a porous separator impregnated with a non-aqueous electrolyte (anolyte). This protective architecture prevents the active metal from deleterious reaction with the environment on the other (cathode) side of the impervious layer, which may include aqueous or non-aqueous liquid electrolytes (catholytes) and/or a variety electrochemically active materials, including liquid, solid and gaseous oxidizers. Safety additives and designs that facilitate manufacture are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/695,054, filed Nov. 15, 2019, now allowed, which is a continuation ofU.S. patent application Ser. No. 15/487,364, filed Apr. 13, 2017, nowissued as U.S. Pat. No. 10,529,971 on Jan. 7, 2020, which is acontinuation of U.S. patent application Ser. No. 15/150,231, filed May9, 2016, now issued as U.S. Pat. No. 9,666,850 on May 30, 2017, which isa continuation of U.S. patent application Ser. No. 14/156,267, filedJan. 15, 2014, now issued as U.S. Pat. No. 9,368,775 on Jun. 14, 2016,which claims priority to U.S. Provisional Patent Application No.61/763,412 filed Feb. 11, 2003, titled PROTECTED LITHIUM ELECTRODESHAVING A POROUS ELECTROLYTE INTERLAYER AND BATTERY CELLS THEREOF; and isa continuation-in-part of U.S. patent application Ser. No. 13/929,653,filed Jun. 27, 2013, titled LITHIUM BATTERY HAVING A PROTECTED LITHIUMELECTRODE AND AN IONIC LIQUID CATHOLYTE, now U.S. Pat. No. 8,828,580;which is a continuation of U.S. patent application Ser. No. 13/615,351,filed Sep. 13, 2012, titled PROTECTED LITHIUM ELECTRODES HAVING APOLYMER ELECTROLYTE INTERLAYER AND BATTERY CELLS THEREOF, now U.S. Pat.No. 8,501,339; which is a continuation of U.S. patent application Ser.No. 12/888,154, filed Sep. 22, 2010, titled PROTECTED ACTIVE METALELECTRODE AND BATTERY CELL WITH TONICALLY CONDUCTIVE PROTECTIVEARCHITECTURE, now U.S. Pat. No. 8,293,398; which is a continuation ofU.S. patent application Ser. No. 11/824,597, filed Jun. 28, 2007, titledPROTECTED ACTIVE METAL ELECTRODE AND BATTERY CELL STRUCTURES WITHNON-AQUEOUS INTERLAYER ARCHITECTURE, now U.S. Pat. No. 7,829,212; whichis a divisional of U.S. patent application Ser. No. 10/824,944, filedApr. 14, 2004, titled PROTECTED ACTIVE METAL ELECTRODE AND BATTERY CELLSTRUCTURES WITH NON-AQUEOUS INTERLAYER ARCHITECTURE, now U.S. Pat. No.7,282,295; which in turn claims priority to U.S. Provisional PatentApplication No. 60/542,532 filed Feb. 6, 2004, titled PROTECTED ACTIVEMETAL ELECTRODE AND BATTERY CELL STRUCTURES WITH NON-AQUEOUS INTERLAYERARCHITECTURE; and U.S. Provisional Patent Application No. 60/548,231filed Feb. 27, 2004, titled VARIATIONS ON PROTECTED ACTIVE METALELECTRODE AND BATTERY CELL STRUCTURES WITH NON-AQUEOUS INTERLAYERARCHITECTURE.

Application Ser. No. 14/156,267 also claims the benefit of U.S.Provisional Patent Application No. 61/763,412 filed Feb. 11, 2013,titled PROTECTED LITHIUM ELECTRODES HAVING A POROUS ELECTROLYTEINTERLAYER AND BATTERY CELLS THEREOF.

The disclosures of all these prior applications are incorporated hereinby reference in their entirety and for all purposes.

STATEMENT OF GOVERNMENT SUPPORT

This invention was made with Government support under Award No.:DE-AR0000349 awarded by the Advanced Research Projects Agency-Energy(ARPA-E), U.S. Department of Energy. The Government has certain rightsin this invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to active metal electrochemicaldevices. More particularly, this invention relates to an active metal(e.g., alkali metals, such as lithium), active metal intercalation (e.g.lithium-carbon, carbon) and active metal alloys (e.g., lithium-tin)alloys or alloying metals (e.g., tin) electrochemical (e.g., electrode)structures and battery cells. The electrode structures have ionicallyconductive protective architecture including an active metal (e.g.,lithium) conductive impervious layer separated from the electrode(anode) by a porous separator impregnated with a non-aqueouselectrolyte. This protective architecture prevents the active metal fromdeleterious reaction with the environment on the other (cathode) side ofthe impervious layer, which may include aqueous, air or organic liquidelectrolytes and/or electrochemically active materials.

2. Description of Related Art

The low equivalent weight of alkali metals, such as lithium, render themparticularly attractive as a battery electrode component. Lithiumprovides greater energy per volume than the traditional batterystandards, nickel and cadmium. Unfortunately, no rechargeable lithiummetal batteries have yet succeeded in the market place.

The failure of rechargeable lithium metal batteries is largely due tocell cycling problems. On repeated charge and discharge cycles, lithium“dendrites” gradually grow out from the lithium metal electrode, throughthe electrolyte, and ultimately contact the positive electrode. Thiscauses an internal short circuit in the battery, rendering the batteryunusable after a relatively few cycles. While cycling, lithiumelectrodes may also grow “mossy” deposits that can dislodge from thenegative electrode and thereby reduce the battery's capacity.

To address lithium's poor cycling behavior in liquid electrolytesystems, some researchers have proposed coating the electrolyte facingside of the lithium negative electrode with a “protective layer.” Suchprotective layer must conduct lithium ions, but at the same time preventcontact between the lithium electrode surface and the bulk electrolyte.Many techniques for applying protective layers have not succeeded.

Some contemplated lithium metal protective layers are formed in situ byreaction between lithium metal and compounds in the cell's electrolytethat contact the lithium. Most of these in situ films are grown by acontrolled chemical reaction after the battery is assembled. Generally,such films have a porous morphology allowing some electrolyte topenetrate to the bare lithium metal surface. Thus, they fail toadequately protect the lithium electrode.

Various pre-formed lithium protective layers have been contemplated. Forexample, U.S. Pat. No. 5,314,765 (issued to Bates on May 24, 1994)describes an ex situ technique for fabricating a lithium electrodecontaining a thin layer of sputtered lithium phosphorus oxynitride(“LiPON”) or related material. LiPON is a glassy single ion conductor(conducts lithium ion) that has been studied as a potential electrolytefor solid state lithium microbatteries that are fabricated on siliconand used to power integrated circuits (See U.S. Pat. Nos. 5,597,660,5,567,210, 5,338,625, and 5,512,147, all issued to Bates et al.).

Work in the present applicants' laboratories has developed technologyfor the use of glassy or amorphous protective layers, such as LiPON, inactive metal battery electrodes. (See, for example, U.S. Pat. No.6,025,094, issued Feb. 15, 2000, U.S. Pat. No. 6,402,795, issued Jun.11, 2002, U.S. Pat. No. 6,214,061, issued Apr. 10, 2001 and U.S. Pat.No. 6,413,284, issued Jul. 2, 2002, all assigned to PolyPlus BatteryCompany).

Prior attempts to use lithium anodes in aqueous environments reliedeither on the use of very basic conditions such as use of concentratedaqueous KOH to slow down the corrosion of the Li electrode, or on theuse of polymeric coatings on the Li electrode to impede the diffusion ofwater to the Li electrode surface. In all cases however, there wassubstantial reaction of the alkali metal electrode with water. In thisregard, the prior art teaches that the use of aqueous cathodes orelectrolytes with Li-metal anodes is not possible since the breakdownvoltage for water is about 1.2 V and a Li/water cell can have a voltageof about 3.0 V. Direct contact between lithium metal and aqueoussolutions results in violent parasitic chemical reaction and corrosionof the lithium electrode for no useful purpose. Thus, the focus ofresearch in the lithium metal battery field has been squarely on thedevelopment of effective non-aqueous (mostly organic) electrolytesystems.

SUMMARY OF THE INVENTION

The present invention relates generally to active metal electrochemicaldevices. More particularly, this invention relates to an active metal(e.g., alkali metals, such as lithium), active metal intercalation (e.g.lithium-carbon, carbon) and active metal alloys (e.g., lithium-tin,lithium-silicon) alloys or alloying metals (e.g., tin, silicon)electrochemical (e.g., electrode) structures and battery cells. Theelectrochemical structures have ionically conductive protectivearchitecture including an active metal (e.g., lithium) ion conductivesubstantially impervious layer separated from the electrode (anode) by aporous separator impregnated with a non-aqueous electrolyte (anolyte).This protective architecture prevents the active metal from deleteriousreaction with the environment on the other (cathode) side of theimpervious layer, which may include aqueous, air or organic liquidelectrolytes (catholytes) and/or electrochemically active materials.

The separator layer of the protective architecture prevents deleteriousreaction between the active metal (e.g., lithium) of the anode and theactive metal ion conductive substantially impervious layer. Thus, thearchitecture effectively isolates (de-couples) the anode/anolyte fromsolvent, electrolyte processing and/or cathode environments, includingsuch environments that are normally highly corrosive to Li or otheractive metals, and at the same time allows ion transport in and out ofthese potentially corrosive environments.

Various embodiments of the cells and cell structures of the presentinvention include active metal, active metal-ion, active metal alloyingmetal, and active metal intercalating anode materials protected with anionically conductive protective architecture having a non-aqueousanolyte. These anodes may be combined in battery cells with a variety ofpossible cathode systems, including water, air, metal hydride and metaloxide cathodes and associated catholyte systems, in particular aqueouscatholyte systems.

Safety additives may also be incorporated into the structures and cellsof the present invention for the case where the substantially imperviouslayer of the protective architecture (e.g., a glass or glass-ceramicmembrane) cracks or otherwise breaks down and allows the aggressivecatholyte to enter and approach the lithium electrode. The non-aqueousinterlayer architecture can incorporate a gelling/polymerizing agentthat, when in contact with the reactive catholyte, leads to theformation of an impervious polymer on the lithium surface. For example,the anolyte may include a monomer for a polymer that is insoluble orminimally soluble in water, for example dioxolane (Diox)/polydioxaloaneand the catholyte may include a polymerization initiator for themonomer, for example, a protonic acid.

In addition, the structures and cells of the present invention may takeany suitable form. One advantageous form that facilitates fabrication isa tubular form.

In one aspect, the invention pertains to an electrochemical cellstructure. The structure includes an anode composed of an active metal,active metal-ion, active metal alloy, active metal alloying metal oractive metal intercalating material. The anode has an ionicallyconductive protective architecture on its surface. The architectureincludes an active metal ion conducting separator layer that has anon-aqueous anolyte and is chemically compatible with the active metaland in contact with the anode, and a substantially impervious ionicallyconductive layer chemically compatible with the separator layer andaqueous environments and in contact with the separator layer. Theseparator layer may be, a semi-permeable membrane impregnated with anorganic anolyte, for example, a micro-porous polymer impregnated with aliquid or gel phase anolyte. Such an electrochemical (electrode)structure may be paired with a cathode system, including an aqueouscathode system, to form battery cells in accordance with the presentinvention.

The structures and battery cells incorporating the structures of thepresent invention may have various configurations, including prismaticand cylindrical, and compositions, including active metal ion, alloy andintercalation anodes, aqueous, water, air, metal hydride and metal oxidecathodes, and aqueous, organic or ionic liquid catholytes; electrolyte(anolyte and/or catholyte) compositions to enhance the safety and/orperformance of the cells; and fabrication techniques.

These and other features of the invention are further described andexemplified in the detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an electrochemical structure cellincorporating an ionically conductive protective interlayer architecturein accordance with the present invention.

FIG. 2 is a schematic illustration of a battery cell incorporating anionically conductive protective interlayer architecture in accordancewith the present invention.

FIGS. 3A-C illustrate embodiments of battery cells in accordance withthe present invention that use a tubular protected anode design.

FIGS. 4-6 are plots of data illustrating the performance of variouscells incorporating anodes with ionically conductive protectiveinterlayer architecture in accordance with the present invention.

FIG. 7 illustrates a Li/water battery and hydrogen generator for a fuelcell in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to specific embodiments of theinvention. Examples of the specific embodiments are illustrated in theaccompanying drawings. While the invention will be described inconjunction with these specific embodiments, it will be understood thatit is not intended to limit the invention to such specific embodiments.On the contrary, it is intended to cover alternatives, modifications,and equivalents as may be included within the spirit and scope of theinvention as defined by the appended claims. In the followingdescription, numerous specific details are set forth in order to providea thorough understanding of the present invention. The present inventionmay be practiced without some or all of these specific details. In otherinstances, well known process operations have not been described indetail so as to not unnecessarily obscure the present invention.

When used in combination with “comprising,” “a method comprising,” “adevice comprising” or similar language in this specification and theappended claims, the singular forms “a,” “an,” and “the” include pluralreference unless the context clearly dictates otherwise. Unless definedotherwise, all technical and scientific terms used herein have the samemeaning as commonly understood to one of ordinary skill in the art towhich this invention belongs.

Introduction

Active metals are highly reactive in ambient conditions and can benefitfrom a barrier layer when used as electrodes. They are generally alkalimetals such (e.g., lithium, sodium or potassium), alkaline earth metals(e.g., calcium or magnesium), and/or certain transitional metals (e.g.,zinc), and/or alloys of two or more of these. The following activemetals may be used: alkali metals (e.g., Li, Na, K), alkaline earthmetals (e.g., Ca, Mg, Ba), or binary or ternary alkali metal alloys withCa, Mg, Sn, Ag, Zn, Bi, Al, Cd, Ga, In. Preferred alloys include lithiumaluminum alloys, lithium silicon alloys, lithium tin alloys, lithiumsilver alloys, and sodium lead alloys (e.g., Na₄Pb). A preferred activemetal electrode is composed of lithium.

The low equivalent weight of alkali metals, such as lithium, render themparticularly attractive as a battery electrode component. Lithiumprovides greater energy per volume than the traditional batterystandards, nickel and cadmium. However, lithium metal or compoundsincorporating lithium with a potential near that (e.g., within about avolt) of lithium metal, such as lithium alloy and lithium-ion (lithiumintercalation) anode materials, are highly reactive to many potentiallyattractive electrolyte and cathode materials. This invention describesthe use of a non-aqueous electrolyte interlayer architecture to isolatean active metal (e.g., alkali metal, such as lithium), active metalalloy or active metal-ion electrode (usually the anode of a batterycell) from ambient and/or the cathode side of the cell. The architectureincludes an active metal ion conducting separator layer with anon-aqueous anolyte (i.e., electrolyte about the anode), the separatorlayer being chemically compatible with the active metal and in contactwith the anode, and a substantially impervious ionically conductivelayer chemically compatible with the separator layer and aqueousenvironments and in contact with the separator layer. The non-aqueouselectrolyte interlayer architecture effectively isolates (de-couples)the anode from ambient and/or cathode, including catholyte (i.e.,electrolyte about the cathode) environments, including such environmentsthat are normally highly corrosive to Li or other active metals, and atthe same time allows ion transport in and out of these potentiallycorrosive environments. In this way, a great degree of flexibility ispermitted the other components of an electrochemical device, such as abattery cell, made with the architecture. Isolation of the anode fromother components of a battery cell or other electrochemical cell in thisway allows the use of virtually any solvent, electrolyte and/or cathodematerial in conjunction with the anode. Also, optimization ofelectrolytes or cathode-side solvent systems may be done withoutimpacting anode stability or performance.

There are a variety of applications that could benefit from the use ofaqueous solutions, including water and water-based electrolytes, air,and other materials reactive to lithium and other active metals,including organic solvents/electrolytes and ionic liquids, on thecathode side of the cell with an active (e.g., alkali, e.g., lithium)metal or active metal intercalation (e.g., lithium alloy or lithium-ion)anode in a battery cell.

The use of lithium intercalation electrode materials like lithium-carbonand lithium alloy anodes (e.g., those based on Sn and Si), andcombinations thereof, rather than lithium metal, for the anode can alsoprovide beneficial battery characteristics. First of all, it allows theachievement of prolonged cycle life of the battery without risk offormation of lithium metal dendrites that can grow from the Li surfaceto the membrane surface causing the membrane's deterioration. Also, theuse of lithium-carbon and lithium alloy anodes in some embodiments ofthe present invention instead of lithium metal anode can significantlyimprove a battery's safety because it avoids formation of highlyreactive “mossy” lithium during cycling.

The present invention describes a protected active metal, alloy orintercalation electrode that enables very high energy density lithiumbatteries such as those using aqueous electrolytes or other electrolytesthat would otherwise adversely react with lithium metal, for example.Examples of such high energy battery couples are lithium-air,lithium-water lithium-metal hydride, lithium-metal oxide, and thelithium alloy and lithium-ion variants of these. The cells of theinvention may incorporate additional components in their electrolytes(anolytes and catholytes) to enhance cell safety, and may have a varietyof configurations, including planar and tubular/cylindrical.

Non-Aqueous Interlayer Architecture

The non-aqueous interlayer architecture of the present invention isprovided in an electrochemical cell structure, the structure having ananode composed of a material selected from the group consisting ofactive metal, active metal-ion, active metal alloy, active metalalloying and active metal intercalating material, and an ionicallyconductive protective architecture on a first surface of the anode. Thearchitecture is composed of an active metal ion conducting separatorlayer with a non-aqueous anolyte, the separator layer being chemicallycompatible with the active metal and in contact with the anode, and asubstantially impervious ionically conductive layer chemicallycompatible with the separator layer and aqueous environments and incontact with the separator layer. The separator layer may include asemi-permeable membrane, for example, a micro-porous polymer, such asare available from Celgard, Inc. Charlotte, N.C., impregnated with anorganic anolyte.

In some embodiments, the porous separator layer is flexible. Forinstance the separator may be a porous polymeric material layer, such asa porous polyolefin (e.g., polyethyelenes or polypropylenes), porouspolytetraflouroethylene layer (e.g., expanded PTFE), porous polyethyleneterepthalate (PET) or some combination thereof such as a polyolefinmulti-layer (e.g., a tri-layer) or a multi-layer of a porous PET or PTFElayer combined (e.g., by lamination to another layer or some other meansof adhering the layers such as using a porous adhesives or chemicaldissolution bonding) with a porous polyolefin layer to provide enhancedchemical compatibility in contact with lithium metal (e.g., a bi-layerwhere the polyolefin layer contacts the lithium) or the PTFE layer orPET layer may be sandwiched between two different porous polymer layers(e.g., between two polyolefin layers). The porous polymer layers may beprocessed using dry or wet methods, as are known in the batteryseparator arts. In the dry process, the film can be stretched tointroduce micropores. The porous polymer layer may further be a nonwovenfilm or coating, which is processed from polymeric fibers into a film orcoating.

The porous polymeric separator material layer is not limited topolyolefins, PTFE, or PET specifically but is understood to include alltypes of polymers which can be fabricated into a porous material layerincluding polyvinylidene fluoride (PVdF), polycarbonates, cellulosics,polyurethanes, polyesters, polyethers, polyacrylates, copolyetheresters, copolyether amides, polyethyelene (PE), polypropylene (PP),polyacrylates, copolyether esters, copolyether amides, chitosn, andfluoropolymers generally.

Suitable fluoropolymers include expanded PTFE as taught in U.S. Pat. No.3,953,566, which is hereby incorporated by reference for the purpose ofdisclosing this composition and methods for its fabrication and use. Forinstance, and as described above, to stabilize the porous PTFE membranefor direct contact with lithium, the PTFE layer may be sandwiched on oneor both sides by a polymer layer of different composition, e.g., apolyolefin.

In various embodiments, the porous separator serving as interlayer maybe a porous polymer layer or multilayer devoid of other materialadditives, or in other embodiments the separator layer may be acomposite of a polymer (e.g., serving as the base material layer) and asecond material such as a ceramic, for example a metal oxide, (e.g.,ceramic metal oxide particles) disposed in pores of the polymer layer ora porous ceramic coating or thin porous ceramic film disposed on one orboth polymer surface (e.g., sandwiching the polymer layer). Forinstance, a nano-porous ceramic film may be used. In some embodiments,the ceramic (be it a particle or film) is non-conductive to lithium ionsand in other embodiments the ceramic is a lithium ion conductor.Suitable ceramic materials which may be used as a ceramic particle inthe pores of a porous layer, typically a polymeric layer, serving as thebase layer of the separator include metal oxides generally, and inparticular the following: alumina (e.g., Al₂O₃), magnesia (e.g., MgO),LiAlO₂, lithium oxide, titanium oxide, magnesium oxide, aluminum oxide,zirconia (i.e., zirconium oxide), hafnium oxide, iron oxide, silica,barium titanate, and yttrium oxide. Other ceramic materials which areconductive of lithium ions and may be used as a ceramic particle orporous ceramic film include lithium titanium phosphates and the like aswell as lithium ion conducting garnets, as described in more detailbelow.

Other particularly suitable materials as a ceramic particle or ceramicfilm or coating are lithium ion conducting oxides having a garnet likestructures. These include Li₆B aLa₂Ta₂O₁₂; Li₇La₃Zr₂Oi₂, Li₅La₃Nb₂O₁₂,Li₅La₃M₂O₁₂ (M=Nb, Ta)Li_(7+x)A_(x)La_(3−x)Zr₂O₁₂ where A may be Zn.These materials and methods for making them are described in U.S. PatentApplication Pub. No.: 2007/0148533 (application Ser. No. 10/591,714) andis hereby incorporated by reference for disclosure of these materialsand methods for their making and use, and suitable garnet likestructures, described, for example, in International Patent ApplicationPub. No.: WO/2009/003695, which is hereby incorporated by reference fordisclosure of these materials and methods for their making and use.Suitable ceramic active metal ion conductors are described, for example,in U.S. Pat. No. 4,985,317 to Adachi et al., incorporated by referenceherein for disclosure of these materials and methods for their makingand use. LiM₂(PO₄)₃ where M may be Ti, Zr, Hf, Ge and relatedcompositions such as those into which certain ion substitutions are madeincluding Li_(1+x)Ti_(2−x)Al_(x)(PO₄)₃ and the like which are known inthe lithium battery arts.

In various embodiments, the ceramic particle or porous ceramic film maybe composed in whole or in part of lithium ion conductive materialswhich are suitable for use herein as the lithium ion conducting materialof the substantially impervious membrane layer, and which are describedin more detail below in the section on the second material layer (i.e.,the substantially impervious layer). In other embodiments theaforementioned porous ceramic film or coating may be sandwiched betweentwo porous polymeric layers.

While the porous separators described herein above are generallyflexible, for instance having an elastic modulus (i.e., Young's modulus)in the range of less than 10 GPa, the invention is not so limited, andit is contemplated that rigid porous material layers may also serve asan interlayer (e.g., those having an elastic modulus greater than 10 GPasuch). Such rigid layers include porous ceramic layers, porous metallayers, porous carbon foam layers and porous glass layers and whichoptionally may serve as a layer on the surface of a porous polymerlayer, or porous polymer layer may be coated on the surface of theceramic, metal or glass layer and thereon serve to provide somestability in contact with lithium metal (e.g., the surface layer apolyolefin), or the porous rigid layer (be it a polycrystalline metaloxide (e.g., a ceramic) or glass, or metal, may be sandwiched betweentwo porous polymer layers. For instance a porous ceramic layer ofalumina such as anodized alumina may be used.

In some embodiments, the ceramic particles are conductive of alkalimetal ions, or conductive of electrons or otherwise insulating orsemiconducting. In some embodiments, the particles may be nanoparticles. In some embodiments, the ceramic particles or ceramic layersmay be reactive to lithium metal in contact, and thereby serve as agetter for shorting dendrites which may grow as a result of cellcycling. Suitable reactive ceramic layers include intercalationmaterials which may in contact with lithium metal reduce and intercalatelithium ions. Such intercalation materials are known in the lithium ionbattery art and include titanium, tungsten, cobalt, and manganese oxidesand the like.

In some embodiments, the porous separator layer has a polymeric baselayer impregnated with a lithium ion conductive ceramic component,typically in particle form.

In some embodiments, the separator layer may be a composite of a porouspolymeric base layer having ceramic filler particles disposed in poresof the base layer and further comprising a polymer capable of swellingor being gelled by a liquid electrolyte and thus serving in theseparator as a gel material. Other materials which may be incorporatedin the separator include ion exchange resin like materials, such as ionexchange polymeric materials, typically having functional groups thatprovide ion exchange properties, such as carboxylic, sulfonic andphosphonic groups. Suitable gel materials are known in the lithiumbattery art, and include copolymers of vinylidene fluoride withhexafluoropropylene (PVDF-HFP), poly(methyl methacrylate (PMMA),poly(acrylonitrile) (PAN) and polyethyelene oxide (PEO)

In the aforementioned embodiments, the separator layer may be furtherimpregnated with a gelling agent, which is typically a polymer materialcapable of being swelled by the liquid electrolyte which is incorporatedtherein.

Material layers suitable for use herein as an interlayer component inthe instant protected electrodes include those described in U.S. Pub.No.: 2012/0169016 to Hisano et al., published Jul. 5, 2012; U.S. Pat.No. 6,242,135 to Mushiake, U.S. Pat. Nos. 3,953,566; 4,187,390;4,539,256; 4,429,000; 4,726,989; 4,100,238; 3,679,540, all of which arehereby incorporated by reference for disclosure of these materials, aswell as those manufactured by Celgard LLC (e.g., PE, PP and PP/PE/PP),Asahi Kasei chemicals (e.g., Hipore); Entek Membranes (e.g., Separion),ExxonMobil/Tonen, SK Energy, Evonik, and DuPont (e.g., the Energain).Other suitable material layers which may serve herein as an interlayerinclude those which are described by S. S. Zhang in an article publishedin the Journal of Power of Sources 164 (2007) 351-364.

In yet other embodiments, the porous interlayer may include or becomposed of an inorganic matrix material such as a porous layer composedof inorganic fibers, such as glass and/or ceramic fibers; the layerbeing thin (e.g., less than 50 um) or thick. In embodiments wherein theglass or ceramic fiber contacts the active metal anode, the compositionof the fiber should be chemically compatible with the active metalanode; e.g., for embodiments wherein the glass or ceramic fiber contactsthe lithium metal anode layer. For instance, a glass or ceramic mat iscontemplated for use herein as an interlayer. Glass mats are known fortheir use as battery separators, especially for lead acid batteries(e.g., an AGM separator). AGM stands for absorptive glass mat and itgenerally a non-woven fabric made with glass microfibers.

In addition to microporous separator layers, non-woven fabric typeseparators may be used as an interlayer or interlayer component herein,including those described in U.S. Pat. No. 5,002,843 to Cieslak, whichdiscloses aramid fibers in a non-woven mat format, and is herebyincorporated by reference. Other non-woven fabric type separators may becomposed of glass or other inorganic or organic (e.g., polymeric fiber)fiber like materials. For instance, this may include non-wovenpolyesters and the like. In various embodiments the interlayer is asolid polymer electrolyte such as polyethylene oxide (PEO) andderivatives and blends thereof having a lithium salt (e.g., Li-TFSI)dissolved therein. These include blends such as block co-polymers ofe.g., polystyrene (PS)-block-polyethylene oxide-block-polystyrenecopolymers. Polymers based on block copolymers of PS and PEO aredisclosed in U.S. patent application Ser. No. 12/225,934 and otheruseful compositions are disclosed in US Patent Publication No.:20130066025, US Patent Publication No.: 20110318648 and US PatentPublication No.: 20130273419. Suitable lithium salts for the solidpolymer anolyte interlayer, which are also suitable for anolytes basedon various non-aqueous liquid solvents, include lithiumtrifluoromethansulfonate (LiCF₃SO₃), lithiumbis(trifluoromethanesulfonimidate) (Li(CF₃SO₂)₂N); lithiumbis(trifluoromethanesulfonimide) (Li(C₂F₅SO₂)₂N, lithium perchlorate(LiClO₄), and lithium bis(oxalato)borate (LiB(C₂O₄)₂). The solid polymerelectrolyte may be modified by adding a plasticizer such assuccinonitrile, polysquarate, EC, PC or some combination thereof, whichreduces crystallization and thus generally increases conductivity,especially near room temperature.

The protective architecture of this invention incorporates asubstantially impervious layer of an active metal ion conducting glassor glass-ceramic (e.g., a lithium ion conductive glass-ceramic (LIC-GC))that has high active metal ion conductivity and stability to aggressiveelectrolytes that vigorously react with lithium metal, for example) suchas aqueous electrolytes. Suitable materials are substantiallyimpervious, ionically conductive and chemically compatible with aqueouselectrolytes or other electrolyte (catholyte) and/or cathode materialsthat would otherwise adversely react with lithium metal, for example.Such glass or glass-ceramic materials are substantially gap-free,non-swellable and are inherently ionically conductive. That is, they donot depend on the presence of a liquid electrolyte or other agent fortheir ionically conductive properties. They also have high ionicconductivity, at least 10⁻⁷ S/cm, generally at least 10⁻⁶ S/cm, forexample at least 10⁻⁵ S/cm to 10⁻⁴ S/cm, and as high as 10⁻³ S/cm orhigher so that the overall ionic conductivity of the multi-layerprotective structure is at least 10⁻⁷ S/cm and as high as 10⁻³ S/cm orhigher. The thickness of the layer is preferably about 0.1 to 1000microns, or, where the ionic conductivity of the layer is about 10⁻⁷S/cm, about 0.25 to 1 micron, or, where the ionic conductivity of thelayer is between about 10⁻⁴ about 10⁻³ S/cm, about 10 to 1000 microns,preferably between 1 and 500 microns, and more preferably between 10 and100 microns, for example 20 microns.

Suitable examples of suitable substantially impervious lithium ionconducting layers include glassy or amorphous metal ion conductors, suchas a phosphorus-based glass, oxide-based glass,phosphorus-oxynitride-based glass, sulpher-based glass, oxide/sulfidebased glass, selenide based glass, gallium based glass, germanium-basedglass or boracite glass (such as are described D. P. Button et al.,Solid State Ionics, Vols. 9-10, Part 1, 585-592 (December 1983); ceramicactive metal ion conductors, such as lithium beta-alumina, sodiumbeta-alumina, Li superionic conductor (LISICON), Na superionic conductor(NASICON), and the like; or glass-ceramic active metal ion conductors.Specific examples include LiPON, Li₃PO₄.Li₂S.SiS₂, Li₂S.GeS₂.Ga₂S₃,Li₂O.₁₁Al₂O₃, Na₂O.₁₁Al₂O₃, (Na, Li)_(1+x)Ti_(2−x)Al_(x)(PO₄)₃(0.6≤x≤0.9) and crystallographically related structures, Na₃Zr₂Si₂PO₁₂,Li₃Zr₂Si₂PO₁₂, Na₅ZrP₃O₁₂, Na₅TiP₃O₁₂, Na₃Fe₂P₃O₁₂, Na₄NbP₃O₁₂,Li₅ZrP₃O₁₂, Li₅TiP₃O₁₂, Li₃Fe₂P₃O₁₂ and Li₄NbP₃O₁₂, and combinationsthereof, optionally sintered or melted. Suitable ceramic ion activemetal ion conductors are described, for example, in U.S. Pat. No.4,985,317 to Adachi et al., incorporated by reference herein in itsentirety and for all purposes.

A particularly suitable glass-ceramic material for the substantiallyimpervious layer of the protective architecture is a lithium ionconductive glass-ceramic having the following composition:

Composition mol % P₂O₅ 26-55% SiO₂ 0-15% GeO₂ + TiO₂ 25-50% in whichGeO₂ 0-50% TiO₂ 0-50% ZrO₂ 0-10% M₂O₃ 0-10% Al₂O₃ 0-15% Ga₂O₃ 0-15% Li₂O3-25%and containing a predominant crystalline phase composed ofLi_(1+x)(M,Al,Ga)_(x)(Ge_(1−y)Ti_(y))_(2−x)(PO₄)₃ where X≤0.8 and0≤Y≤1.0, and where M is an element selected from the group consisting ofNd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb, and/orLi_(1+x+y)Q_(x)Ti_(2−x)Si_(y)P_(3−y)O₁₂ where 0<X≤0.4 and 0<Y≤0.6, andwhere Q is Al or Ga. The glass-ceramics are obtained by melting rawmaterials to a melt, casting the melt to a glass and subjecting theglass to a heat treatment. Such materials are available from OHARACorporation, Japan and are further described in U.S. Pat. Nos.5,702,995, 6,030,909, 6,315,881 and 6,485,622, incorporated herein byreference for disclosure of these materials and methods of making them.

Such lithium ion conductive substantially impervious layers andtechniques for their fabrication and incorporation in battery calls aredescribed in U.S. Provisional Patent Application No. 60/418,899, filedOct. 15, 2002, titled IONICALLY CONDUCTIVE COMPOSITES FOR PROTECTION OFANODES AND ELECTROLYTES, its corresponding U.S. patent application Ser.No. 10/686,189 (Attorney Docket No. PLUSP027), filed Oct. 14, 2003, andtitled IONICALLY CONDUCTIVE COMPOSITES FOR PROTECTION OF ACTIVE METALANODES, U.S. patent application Ser. No. 10/731,771 (Attorney Docket No.PLUSP027X1), filed Dec. 5, 2003, and titled IONICALLY CONDUCTIVECOMPOSITES FOR PROTECTION OF ACTIVE METAL ANODES, and U.S. patentapplication Ser. No. 10/772,228 (Attorney Docket No. PLUSP039), filedFeb. 3, 2004, and titled IONICALLY CONDUCTIVE MEMBRANES FOR PROTECTIONOF ACTIVE METAL ANODES AND BATTERY CELLS. These applications areincorporated by reference herein in their entirety for all purposes.

Another particularly suitable material for the second layer of theprotective composite is a lithium ion conducting oxide having a garnetlike structure. These include Li₆BaLa₂Ta₂O₁₂; Li₇La₃Zr₂O₁₂,Li₅La₃Nb₂O₁₂, Li₅La₃M₂O₁₂ (M=Nb, Ta)Li_(7+x)A_(x)La_(3−x)Zr₂O₁₂ where Amay be Zn. These materials and methods for making them are described inU.S. Patent Application Pub. No.: 2007/0148533 (application Ser. No.10/591,714) and is hereby incorporated by reference, and suitable garnetlike structures, are described in International Patent Application Pub.No.: WO/2009/003695 which is hereby incorporated by reference.

A critical limitation in the use of these highly conductive glasses andglass-ceramics in lithium (or other active metal or active metalintercalation) batteries is their reactivity to lithium metal orcompounds incorporating lithium with a potential near that (e.g., withinabout a volt) of lithium metal. The non-aqueous electrolyte interlayerof the present invention isolates the lithium (for example) electrodefrom reacting with the glass or glass-ceramic membrane. The non-aqueousinterlayer may have a semi-permeable membrane, such as a Celgardmicro-porous separator, to prevent mechanical contact of the lithiumelectrode to the glass or glass-ceramic membrane. The membrane isimpregnated with organic liquid electrolyte (anolyte) with solvents suchas ethylene carbonate (EC), propylene carbonate (PC), 1,2-dimethoxyethane (DME), 1,3-dioxolane (DIOX), or various ethers, glymes, lactones,sulfones, sulfolane, or mixtures thereof. It may also or alternativelyhave a polymer electrolyte, a gel-type electrolyte, or a combination ofthese. The important criteria are that the lithium electrode is stablein the non-aqueous anolyte, the non-aqueous anolyte is sufficientlyconductive to Li⁺ ions, the lithium electrode does not directly contactthe glass or glass-ceramic membrane, and the entire assembly allowslithium ions to pass through the glass or glass-ceramic membrane.

In various embodiments the liquid impermeable solid electrolyte membrane(i.e., the substantially impervious layer) may be a glass, glass-ceramicor ceramic membrane composed in whole or in part of an active metal ionconducting solid-state electrolyte material. For instance, the membranefabricated by sintering a pellet or tape cast layer of said solid-stateelectrolyte material, including sintering of a tape cast glass materialthat in the process of densification during sintering crystallizes to ahighly conductive phase.

Particularly suitable solid-state electrolyte materials include thefollowing:

(i) garnet like compounds as described in PCT Patent Application WO2013/010692 having Robert Bosch GMBH as applicant and inventors Eisele,Koehler, Hinderberger, Logeat, and Kozinsky and which is hereinincorporated by reference:

Li_(n)[A_((3−a′−a″))A′_((a′))A″_((a″))][B_((2−b′−b″))B′_((b′))B″_((b″))][C′_((c′))C″_((c″)])]O₁₂wherein

-   -   A represents at least one element selected from the group        consisting of La, Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and        Yb;    -   A′ represents at least one element selected from the group        consisting of Ca, Sr, and Ba;    -   A″ represents at least one element selected from the group        consisting of Na and K;    -   with 0≤a′<2 and 0≤a″<1    -   B represents at least one element selected from the group        consisting of Zr, Hf, and Sn;    -   B′ represents at least one element selected from the group        consisting of Ta, Nb, Sb, and Bi;    -   B″ represents at least one element selected from the group        consisting of Te, W, and Mo    -   with 0≤b′≤2 and 0≤b″≤2;    -   C′ represents at least one element selected from the group        consisting of Al and Ga;    -   C″ represents at least one element selected from the group        consisting of Si and Ge;    -   with 0≤c′≤0.5 and 0≤c″≤0.4    -   and n=7+a′+2a″−b′−2b″−3c′−4c″ and 5.5≤n≤6.875 (or 5≤n≤7).    -   Particular examples include but are not limited to:        Li_(6.875)La₃Ta_(0.125)Zr_(1.875)O₁₂;        Li_(6.75)La₃Ta_(0.25)Zr_(1.75)O₁₂;        Li_(6.5)La₃Ta_(0.5)Zr_(1.5)O₁₂;        Li_(6.25)La₃Ta_(0.75)Zr_(1.25)O₁₂; Li₆La₃TaZrO₁₂;        Li_(5.5)La₃Ta_(1.5)Zr_(0.5)O₁₂; Al_(0.1)Li_(6.7)La₃Zr₂O₁₂;        Al_(0.17)Li_(6.49)La₃Zr₂O₁₂; Al_(0.23)Li_(6.31)La₃Zr₂O₁₂;        Al_(0.29)Li_(6.13)La₃Zr₂O₁₂; Al_(0.35)Li_(5.95)La₃Zr₂O₁₂;        Al_(0.3)Li_(5.85)Sr_(0.25) La_(2.75)Nb_(0.5)Zr_(1.5)O₁₂;        Si_(0.2)Li_(6.2)La₃Zr₂O₁₂        (ii) garnet like compounds as described in U.S. Patent        Application Pub. No.: 2011/0244337 having Kabushiki Kaisha        Toyota Chuo Kenkyusho as assignee and inventors Ohta, Kobayashi,        Asaoka, Asai, and which is herein incorporated by reference:

Li_(5+x)La₃(Zr_(X),A_(2−X))O₁₂ wherein

-   -   A is at least one selected from the group consisting of Sc, Ti,        V, Y, Nb, Hf, Ta, Al, Si, Ga, Ge, and Sn and X satisfies the        inequality 1.45≤X<2; or    -   A is one obtained by substituting an element having an ionic        radius different from that of Zr for Zr sites in a garnet type        lithium ion conducting oxide represented by the formula        Li₇La₃Zr₂O₁₂.        (iii) garnet like compounds as described in U.S. Pat. No.        8,092,941 having Werner Weppner as assignee and inventors        Weppner and Thangadurai, and which is herein incorporated by        reference:

Li_(5+x)A_(y)G_(z),M₂O₁₂ wherein

-   -   A is in each case independently a monovalent, divalent,        trivalent, or tetravalent cation (e.g. A is an alkaline earth        metal or transition metal such as Ca, Sr, Ba, Mg and/or Zn;    -   G is in each case independently a monovalent, divalent,        trivalent, or tetravalent cation (e.g. La);    -   M is in each case independently a trivalent, tetravalent, or        pentavalent cation; with 0<x≤3, 0<y≤3, and 0<z≤3 (e.g. a        transition metal such as Nb, Ta, Sb and V); and    -   O can be partially or completely replaced by divalent and/or        trivalent anions such as e.g. N³⁻; and furthermore,    -   within a structure of this formal composition L, A, G and M can        each be the same or different.

For example, Li_(5+x)A_(y)G_(3-x)M₂O₁₂ [such as Li₆ALa₂M₂O₁₂, e.g.,Li₆ALa₂Ta₂O₁₂ (A=Sr, Ba)]

(iv) garnet like compounds as described in U.S. Patent Pub. No.:2011/0053002 having NGK Insulators, Ltd., as assignee and inventorsYamamura, Hattori, Yoshida, Honda, and Sato, and which is hereinincorporated by reference, for instance a ceramic material containing:

-   -   (a) Li, La, Zr, Nb, O; or (b) Li, La, Zr, Ta, O; or (c) Li, La,        Zr, Nb, Ta, O. For example, Li_(a)La_(b)Zr_(x)M_(y)O_(c) wherein        M represents the total number of moles of Nb and Ta, the molar        ratios of the constitutive metal elements containing Nb and Ta        can be set to be a:b:x+y:y=7:3:2:0.1 or greater to 0.6 or lower.        In addition the ceramic material may contain Al (e.g.,        Li_(a)La_(b)Zr_(x)M_(y)O_(c)zAl (wherein M represents the total        number of moles of Nb and Ta and the molar ratios of the        constitutive metal elements can be set to be        a:b:x+y:z=7:3:2:0.025 or greater to 0.35 or lower.        (v) garnet like compounds as described in U.S. Patent Pub. No.:        2010/0203383 having BASF SE, as assignee and inventor Werner        Weppner, and which is herein incorporated by reference, for        instance a compound having the general formula:

Li_(7+x)A_(x)G_(3−x)Zr₂O₁₂ wherein

-   -   A is in each case independently a divalent cation (or        combination of such cations, preferably divalent metal cations        such as alkaline earth metal ions such as Ca, Sr, Ba, and/or Mg        and also divalent cations such as Zn);    -   G is in each case independently a trivalent cation (or        combination of such cations, with preference given to La);    -   with 0≤x≤3 (and preference is given to 0≤x≤2 and in particular        0≤x≤1); and    -   O can be partly or completely replaced by divalent or trivalent        anions such as N³⁻        (vi) nasicon like compounds as described in U.S. Pat. No.        4,985,317 having Japan Synthetic Rubber Co., Ltd. as assignee        and inventors Adachi, Imanaka, Aono, Sugimoto, Sadaoka, Yasuda,        Hara, Nagata, and which is herein incorporated by reference, for        instance a compound (sometimes referred to as LTP) having the        general formula:

Li_(1+x)M_(x)Ti_(2−x)(PO₄)₃ wherein  (a)

M is at least one element selected from the group consisting of Fe, Aland rare earth elements and x is a number from 0.1 to 1.9; or

Li_(1+y)Ti₂Si_(y)P_(3−y)O₁₂ wherein y is a number from 0.1 to 2.9;or  (b)

-   -   (c) or some combination of (a) and (b)        (vii) lithium ion conductive compounds having the following        composition:

Composition Mol % P₂O₅  26-55% SiO₂   0-15% GeO₂ and TiO₂  25-50% inwhich TiO₂   0-50% in which GeO₂   0-50% ZrO₂   0-10% M₂O₃  0 < 10%Al₂O₃  0-15% Ga₂O₃  0-15% Li₂O  3-25%And in particular lithium ion conductive compounds having the followinggeneral formula:

Li_(1+x)(M,Al,Ga)_(x)(Ge_(1-y)Ti_(y))_(2-x)(PO₄)₃ where x≤0.8 and0≤y≤1.0 and where M is an element selected from the group consisting ofNd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb and/orLi_(1+x+y)Q_(x)Ti_(2−x)Si_(y)P_(3−y) O₁₂ where 0<x≤0.4 and 0<y≤0.6 andwhere Q is Al or Ga. For example Li_((1+x))Al_(x)Ti_(2−x)(PO₄)₃ where Xis 0 to 0.8 as described in U.S. Pat. No. 5,702,995 having KabushikiKaisha Ohara as assignee and inventor Jie Fu, and which is hereinincorporated by reference.

Other suitable materials include glassy or amorphous metal ionconductors, such as a phosphorus-based glass, oxide-based glass,phosphorus-oxynitride-based glass, sulpher-based glass, oxide/sulfidebased glass, selenide based glass, gallium based glass, germanium-basedglass, Nasiglass; ceramic active metal ion conductors, such as lithiumbeta-alumina, sodium beta-alumina, Li superionic conductor (LISICON), Nasuperionic conductor (NASICON), and the like; or glass-ceramic activemetal ion conductors. Specific examples include LiPON, Li₃PO₄.Li₂S.SiS₂,Li₂S.GeS₂.Ga₂S₃, Li₂O.11 Al₂O₃, Na₂O.11 Al₂O₃,(Na,Li)_(1+x)Ti_(2−x)Al_(x)(PO₄)₃ (0.1≤x≤0.9) and crystallographicallyrelated structures, Li_(1+x)Hf_(2−x)Al_(x)(PO₄)₃ (0.1≤x≤0.9),Na₃Zr₂Si₂PO₁₂, Li₃Zr₂Si₂PO₁₂, Na₅ZrP₃O₁₂, Na₅TiP₃O₁₂, Na₃Fe₂P₃O₁₂,Na₄NbP₃O₁₂, Na-Silicates, L_(1.3)La_(0.5)TiO₃, Na₅MSi₄O₁₂ (M: rare earthsuch as Nd, Gd, Dy) Li₅ZrP₃O₁₂, Li₅TiP₃O₁₂, Li₃Fe₂P₃O₁₂ and Li₄NbP₃O₁₂,and combinations thereof, optionally sintered or melted. Suitableceramic ion active metal ion conductors are described, for example, inU.S. Pat. No. 4,985,317 to Adachi et al., incorporated by referenceherein in its entirety and for all purposes.

A particularly suitable glass-ceramic material is a lithium ionconductive glass-ceramic having the following composition:

Composition mol % P₂O₅ 26-55% SiO₂ 0-15% GeO₂ + TiO₂ 25-50% in whichGeO₂ 0-50% TiO₂ 0-50% ZrO₂ 0-10% M₂O₃ 0-10% Al₂O₃ 0-15% Ga₂O₃ 0-15% Li₂O3-25%and/or such a material containing a predominant crystalline phasecomposed of Li_(1+x)(M,Al,Ga)_(x)(Ge_(1−y)Ti_(y))_(2−x)(PO₄)₃ whereX=0.8 and 0=Y=1.0, and where M is an element selected from the groupconsisting of Nd, Sm, Eu, Gd, T, Dy, Ho, Er, Tm and Yb and/orLi_(1+x+y)Q_(x)Ti_(2−x)Si_(y)P_(3−y)O₁₂ where 0<X=0.4 and 0<Y=0.6, andwhere Q is Al or Ga. The glass-ceramics are obtained by melting rawmaterials to a melt, casting the melt to a glass and subjecting theglass to a heat treatment. Such materials are available from OHARACorporation, Japan and are further described in U.S. Pat. Nos.5,702,995, 6,030,909, 6,315,881 and 6,485,622, incorporated herein byreference.

Suitable solid-state ion conductor materials for the membrane includeLi₆BaLa₂Ta₂O₁₂; Li₇La₃Zr₂O₂, Li₅La₃Nb₂O₂, Li₅La₃M₂O₁₂ (M=Nb,Ta)Li_(7+x)A_(x)La_(3−x)Zr₂O₁₂ where A may be Zn or another transitionmetal. These materials and methods for making them are described in U.S.Patent Application Pub. No.: 2007/0148533 (application Ser. No.10/591,714) and is hereby incorporated by reference in its entirety andsuitable garnet like structures, are described in International PatentApplication Pub. No.: WO/2009/003695, herein incorporated by referencefor all that it contains.

The garnet structure can be modified by doping different elements soenhance performance such as chemical compatibility, ease of fabrication,reducing cost, and increasing conductivity. Particularly suitablesubstantially impervious garnet like layers include modified garnet likelayers having compositions of about Li₆SrLa₂Ta₂O₁₂, Li₆BaLa₂Ta₂O₁₂,Li₆CaLa₂Nb₂O₁₂, Li₆SrLa₂Nb₂O₁₂, Li₆BaLa₂Nb₂O₁₂, Li₅La₃Bi₂O₁₂,Li₆SrLa₂Bi₂O₁₂, Li₅La₃Nb_(1.9)Y_(0.1)O₁₂, Li₇La₃Hf₂O₁₂,Li_(6.55)La₃Hf_(1.55)Ta_(0.45)O₁₂, Li₅Nd₃Sb₂O₂, Li₇La₃Sn₂O₁₂,Li₇La₃Zr₂O₁₂, Li_(6.75)La₃Zr_(1.75)Nb_(0.25)O₁₂,Li_(6.25)La₃Zr₂Ga_(0.25)O₁₂, Li₇La₃Zr₂O₁₂ (LLZO) doped with Ge, Si, In,Al or some combination thereof

Referring to FIG. 1, a specific embodiment of the present invention isillustrated and described. FIG. 1 shows an unscaled depiction of anelectrochemical cell structure 100 having an active metal, activemetal-ion, active metal alloying metal, or active metal intercalatingmaterial anode 102 and an ionically conductive protective architecture104. The protective architecture 104 has an active metal ion conductingseparator layer 106 with a non-aqueous anolyte (sometimes also referredto as a transfer electrolyte) on a surface of the anode 102 and asubstantially impervious ionically conductive layer 108 in contact withthe separator layer 106. The separator layer 106 is chemicallycompatible with the active metal and the substantially impervious layer108 is chemically compatible with the separator layer 106 and aqueousenvironments. The structure 100 may optionally include a currentcollector 110, composed of a suitable conductive metal that does notalloy with or intercalate the active metal. When the active metal islithium, a suitable current collector material is copper. The currentcollector 110 can also serve to seal the anode from ambient to preventdeleterious reaction of the active metal with ambient air or moisture.

In various embodiments the separator layer 106 is composed of a porousmembrane impregnated with a non-aqueous anolyte. For example, themembrane may be a micro-porous polymer, such as are available fromCelgard, Inc. The non-aqueous anolyte may be in the liquid or gel phase.For example, the anolyte may include a solvent selected from the groupconsisting of organic carbonates, ethers, lactones, sulfones, etc, andcombinations thereof, such as EC, PC, DEC, DMC, EMC, 1,2-DME or higherglymes, THF, 2MeTHF, sulfolane, ionic liquids (as are known in the art)and combinations thereof. 1,3-dioxolane may also be used as an anolytesolvent, particularly but not necessarily when used to enhance thesafety of a cell incorporating the structure, as described furtherbelow. Generally the anolyte should be chemically compatible in contactwith the active metal anode, and in this regard may include compatibleliquid solvents (i.e., those which are solely compatible) as well asthose solvents which are not compatible by themselves but in combinationwith a suitable electrolytic salt and/or additional solvent(s) leads toa chemically compatible anolyte. Such liquid solvents (solely chemicallycompatible or otherwise) may include organic or inorganic solvents suchas those described above, as well as ionic liquid solvents. For instancethe chemically compatible anolyte may be composed of an ionic liquid incombination with non-aqueous organic liquid solvent(s) and an optionalsalt. When the anolyte is in the gel phase, gelling agents such aspolyvinylidine fluoride (PVdF) compounds, hexafluropropylene-vinylidenefluoride copolymers (PVdf-HFP), polyacrylonitrile compounds,cross-linked polyether compounds, polyalkylene oxide compounds,polyethylene oxide compounds, and combinations and the like may be addedto gel the solvents. Suitable anolytes will also, of course, alsoinclude active metal salts, such as, in the case of lithium, forexample, LiPF₆, LiBF₄, LiAsF₆, LiS₃CF₃ or LiN(SO₂C₂F₅)₂. One example ofa suitable separator layer is 1 M LiPF₆ dissolved in propylene carbonateand impregnated in a Celgard microporous polymer membrane.

When the anolyte is in the gel phase it may be used as a freestandinglayer or otherwise as a coating on the lithium metal or on thesubstantially impervious layer. Both organic solvent- and ionicliquid-based gels as well as combinations thereof are contemplated foruse herein as an interlayer.

As described in U.S. Pat. No. 8,332,028, other anolyte solventsincluding ionic liquids, and especially non-aqueous organic ionicliquids, as well as inorganic ionic liquids which are sufficientlycompatible in contact with the lithium anode layer (e.g., lithium metalor lithium intercalation material, such as carbon) may be used asanolyte herein. Ionic liquids are a subclass of non-aqueous solvents andare generally known in the battery art for their use as an electrolytecomponent. Ionic liquids generally suitable for use herein arepreferably liquids at room temperature, although the invention is notlimited as such, and organic salts having melting points below 100° C.are generally contemplated. Ionic liquids are known in the art,including those based on imidazolium and pyrrolidinium. The ionicliquids will generally contain a lithium salt, such as those having aTFSI anion.

As a particular type of non-aqueous electrolyte, ionic liquid basedelectrolytes may be impregnated in a porous membrane (e.g., amicroporous membrane) or caused to swell or gel a polymeric separatormaterial. Typically, the ionic liquid will further comprise a lithiumsalt dissociated therein to provide charge carriers. In some instancesthe ionic liquid may be caused to polymerize, and in such instances, thepolymeric ionic liquid may itself serve as the lithium ion conductingseparator layer. Ionic liquid based electrolytes, including those whichare caused to swell or gel a polymeric separator layer (e.g.,polyvinylidene fluoride [PVdF] or poly-ethylene oxide [PEO]) aresuitable for use herein and are known in the art. Ionic liquids may beclassified according to their cation and anion compositions. For exampleionic liquid cations which are known in the art include those of thePyrrolidinium type (e.g., N-methyl-N-propylpyrrolidinium,N-propyl-N-methylpyrrolidinium [PYR13+], 1-butyl-1-methylpyrrolidinium[PYR14+], Imidazolium (e.g., 1-ethyl-3-methylimidazolium [EMI+]). Forexample ionic liquid anions which are known in the art include those ofthe type bis(trifluoromethanesulfonyl)imide andbis(fluorosulfonyl)imide. A particularly suitable lithium salt is thatof the type lithium bis(trifluoromethanesulfonyl)imide. For example,N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide[PYR14TFSI] and N-Butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide[PYR14FSI] impregnated in a porous separator or caused to gel or swell asuitable polymer such as PEO or PVdF, and having dissolved therein thelithium salt LiTFSI. It should be understand to one of skill in the artthat the search for new and improved ionic liquid based electrolytes (orelectrolytes comprising ionic liquids) for use in lithium batteries isan ongoing worldwide effort, and thus it is contemplated herein thatnovel and hitherto unknown ionic liquids suitable for use herein as ananolyte will be discovered, and especially those having improvedstability against electroactive lithium materials such as lithium metal,and thus will provide particular benefit, and by this expedient suchionic liquids are contemplated herein for use as an anolyte of theinstant protected anode.

Another suitable anolyte includes a solution of a non-aqueous solvent(s)combined with a very high concentration of a lithium salt (e.g., aboutan equimolar complex of liquid solvent with lithium salts); for example,an about equimolar complex of a glyme (e.g., tri-glyme or tetra-glyme)and a lithium salt of lithium bis(trifluoromethanesulfonyl)amide[LiTFSA] or other such as lithium bis(trifluoromethanesulfonyl)imideLiTFSI or lithium bis(fluorosulfonyl)imide. This anolyte may behave likea concentrated solution or an ionic liquid. In some embodiments, fumedsilica or other high surface area particles may be added to the solutionto enhance solution properties and in some instances for making thesolution behave like a semi-solid.

In various embodiments the anolyte may be in the gel phase or theanolyte may be a liquid anolyte swelled in or by a polymer layer. Suchembodiments contemplate gel phase anolytes of non-aqueous organic orionic liquid solvents typically in combination with a salt, orcombinations thereof of a gel phase anolyte comprising both anon-aqueous organic liquid solvent and a suitable ionic liquid solventas described above.

There are a number of advantages of a protective architecture inaccordance with the present invention. In particular, cell structuresincorporating such an architecture may be relatively easilymanufactured. In one example, lithium metal is simply placed against amicro-porous separator impregnated with organic liquid or gelelectrolyte and with the separator adjacent to a glass/glass ceramicactive metal ion conductor.

An additional advantage of the non-aqueous interlayer is realized whenglass-ceramics are used. When amorphous glasses of the type described bythe OHARA Corp. patents cited above are heat-treated, the glassdevitrifies, leading to the formation of a glass-ceramic. However, thisheat treatment can lead to the formation of surface roughness which maybe difficult to coat using vapor phase deposition of an inorganicprotective interlayer such as LiPON, Cu₃N, etc. The use of a liquid (orgel), non-aqueous electrolyte interlayer would easily cover such a roughsurface by normal liquid flow, thereby eliminating the need for surfacepolishing, etc. In this sense, techniques such as “draw-down” (asdescribed by Sony Corporation and Shott Glass (T. Kessler, H. Wegener,T. Togawa, M. Hayashi, and T. Kakizaki, “Large Microsheet Glass for40-in. Class PALC Displays,” 1997, FMC2-3, incorporated herein byreference) could be used to form thin glass layers (20 to 100 microns),and these glasses heat treated to form glass-ceramics.

In yet other embodiments, the interlayer may be integrated with thesecond material layer (i.e., the substantially impervious layer). Forinstance, the second material layer may be a sintered layer of a glass,ceramic or glass ceramic and the porous interlayer integrated therewith.For example, the porous interlayer composed of a substantially similarcomposition and/or crystal structure as that of the second materiallayer (e.g., an anode compatible LTP composition or Garnet likematerial) except that the integrated interlayer is porous and thereforeaccepting of a liquid phase anolyte. For instance, the integratedstructure may be fabricated by tape casting of a multi-layer (e.g., adual layer) wherein at least one of the layers is substantiallyimpervious and the layer opposing the anode (e.g., in direct contact) isporous. In some embodiments, the integrated structure may be furtherpaired with an additional porous interlayer which separates theintegrated layer from the anode and by this expedient allows for the useof an anode incompatible integrated structure into the protectivearchitecture.

In other embodiments, it is contemplated that the substantiallyimpervious layer may be formed on or in conjunction with anelectronically insulating and ionically insulating porous substrate as asupport layer. The substantially impervious layer may be fabricated as acoating or film on the porous support (e.g., the porous support composedof a rigid glass or polycrystalline ceramic or glass-ceramic), or it maybe fabricated using multi-layer tape casting wherein one or more layersare lithium ion conductors and one or more other layers provide aporous, non-conducting support.

In addition, porous metal support layer embodiments are alsocontemplated. Generally when a porous metal support is used it may bepositioned on the surface that opposes the external environment aboutthe protected anode (e.g., that side which opposes the cathode).However, this embodiment is not limited as such and the porous metalsupport may oppose the anode, but in such embodiments an insulatinggenerally porous polymeric separator may be incorporated between theporous metal layer and the lithium layer, for the purpose of providingelectronic isolation therebetween.

In yet a further embodiment, the interlayer may effectively be providedby a gap (i.e., a space) which contains a liquid phase anolyte but nomaterial interlayer. The gap may be incorporated in the anode structureusing any number of suitable constructions, including wherein thesubstantially impervious membrane is attached to a frame (e.g., providedby the battery casing) at a spaced apart distance from the lithium metallayer, and the gap subsequently created there between the layers filledwith liquid anolyte. In other words a liquid anolyte interlayer devoidof a porous solid material layer is contemplated herein.

Battery Cells

The non-aqueous interlayer architecture is usefully adopted in batterycells. For example, the electrochemical structure 100 of FIG. 1 can bepaired with a cathode system 120 to form a cell 200, as depicted in FIG.2. The cathode system 120 includes an electronically conductivecomponent, an ionically conductive component, and an electrochemicallyactive component. The cathode system 120 may have any desiredcomposition and, due to the isolation provided by the protectivearchitecture, is not limited by the anode or anolyte composition. Inparticular, the cathode system may incorporate components which wouldotherwise be highly reactive with the anode active metal, such asaqueous materials, including water, aqueous catholytes and air, metalhydride electrodes and metal oxide electrodes.

In one embodiment, a Celgard separator would be placed against one sideof the thin glass-ceramic, followed by a non-aqueous liquid or gelelectrolyte, and then a lithium electrode. On the other side of theglass ceramic membrane, an aggressive solvent could be used, such as anaqueous electrolyte. In such a way, an inexpensive Li/water or Li/aircell, for example, could be built.

Cathode Systems

As noted above, the cathode system 120 of a battery cell in accordancewith the present invention may have any desired composition and, due tothe isolation provided by the protective architecture, is not limited bythe anode or anolyte composition. In particular, the cathode system mayincorporate components which would otherwise be highly reactive with theanode active metal, such as aqueous materials, including water, aqueoussolutions and air, metal hydride electrodes and metal oxide electrodes.

Battery cells of the present invention may include, without limitation,water, aqueous solutions, air electrodes and metal hydride electrodes,such as are described in co-pending application Ser. No. 10/772,157titled ACTIVE METAU/AQUEOUS ELECTROCHEMICAL CELLS AND SYSTEMS, now U.S.Pat. No. 7,645,543, incorporated herein by reference in its entirety andfor all purposes, and metal oxide electrodes, as used, for example, inconventional Li-ion cells.

The effective isolation between anode and cathode achieved by theprotective interlayer architecture of the present invention also enablesa great degree of flexibility in the choice of catholyte systems, inparticular aqueous systems, but also non-aqueous systems. Since theprotected anode is completely decoupled from the catholyte, so thatcatholyte compatibility with the anode is no longer an issue, solventsand salts which are not kinetically stable to Li can be used.

For cells using water as an electrochemically active cathode material, aporous electronically conductive support structure can provide theelectronically conductive component of the cathode system. An aqueouselectrolyte (catholyte) provides ion carriers for transport(conductivity) of Li ions and anions that combine with Li. Theelectrochemically active component (water) and the ionically conductivecomponent (aqueous catholyte) will be intermixed as a single solution,although they are conceptually separate elements of the battery cell.Suitable catholytes for the Li/water battery cell of the inventioninclude any aqueous electrolyte with suitable ionic conductivity.Suitable electrolytes may be acidic, for example, strong acids like HCl,H₂SO₄, H₃PO₄ or weak acids like acetic acid/Li acetate; basic, forexample, LiOH; neutral, for example, sea water, LiCl, LiBr, LiI; oramphoteric, for example, NH₄Cl, NH₄Br, etc

The suitability of sea water as an electrolyte enables a battery cellfor marine applications with very high energy density. Prior to use, thecell structure is composed of the protected anode and a porouselectronically conductive support structure (electronically conductivecomponent of the cathode). When needed, the cell is completed byimmersing it in sea water which provides the electrochemically activeand ionically conductive components. Since the latter components areprovided by the sea water in the environment, they need not transportedas part of the battery cell prior to it use (and thus need not beincluded in the cell's energy density calculation). Such a cell isreferred to as an “open” cell since the reaction products on the cathodeside are not contained. Such a cell is, therefore, a primary cell.

Secondary Li/water cells are also possible in accordance with theinvention. As noted above, such cells are referred to as “closed” cellssince the reaction products on the cathode side are contained on thecathode side of the cell to be available to recharge the anode by movingthe Li ions back across the protective membrane when the appropriaterecharging potential is applied to the cell.

As noted above and described further below, in another embodiment of theinvention, ionomers coated on the porous catalytic electronicallyconductive support reduce or eliminate the need for ionic conductivityin the electrochemically active material.

The electrochemical reaction that occurs in a Li/water cell is a redoxreaction in which the electrochemically active cathode material getsreduced. In a Li/water cell, the catalytic electronically conductivesupport facilitates the redox reaction. As noted above, while not solimited, in a Li/water cell, the cell reaction is believed to be:

Li+H₂O=LiOH+½H₂.

The half-cell reactions at the anode and cathode are believed to be:

Li=Li⁺ +e ⁻  Anode:

e+H₂O=OH⁻+½H₂  Cathode:

Accordingly, the catalyst for the Li/water cathode promotes electrontransfer to water, generating hydrogen and hydroxide ion. A common,inexpensive catalyst for this reaction is nickel metal; precious metalslike Pt, Pd, Ru, Au, etc. will also work but are more expensive.

Also considered to be within the scope of Li (or other activemetal)/water batteries of this invention are batteries with a protectedLi anode and an aqueous electrolyte composed of gaseous and/or solidoxidants soluble in water that can be used as active cathode materials(electrochemically active component). Use of water soluble compounds,which are stronger oxidizers than water, can significantly increasebattery energy in some applications compared to the lithium/waterbattery, where during the cell discharge reaction, electrochemicalhydrogen evolution takes place at the cathode surface. Examples of suchgaseous oxidants are O₂, SO₂ and NO₂. Also, metal nitrites, inparticular NaNO₂ and KNO₂ and metal sulfites such as Na₂SO₃ and K₂SO₃are stronger oxidants than water and can be easily dissolved in largeconcentrations. Another class of inorganic oxidants soluble in water areperoxides of lithium, sodium and potassium, as well as hydrogen peroxideH₂O₂.

The use of hydrogen peroxide as an oxidant can be especially beneficial.There are at least two ways of utilizing hydrogen peroxide in a batterycell in accordance with the present invention. First of all, chemicaldecomposition of hydrogen peroxide on the cathode surface leads toproduction of oxygen gas, which can be used as active cathode material.The second, perhaps more effective way, is based on the directelectroreduction of hydrogen peroxide on the cathode surface. Inprincipal, hydrogen peroxide can be reduced from either basic or acidicsolutions. The highest energy density can be achieved for a batteryutilizing hydrogen peroxide reduction from acidic solutions. In thiscase a cell with Li anode yields E⁰=4.82 V (for standard conditions)compared to E°=3.05 V for Li/Water couple. However, because of very highreactivity of both acids and hydrogen peroxide to unprotected Li, suchcell can be practically realized only for protected Li anode such as inaccordance with the present invention.

For cells using air as an electrochemically active cathode material, theair electrochemically active component of these cells includes moistureto provide water for the electrochemical reaction. The cells have anelectronically conductive support structure electrically connected withthe anode to allow electron transfer to reduce the air cathode activematerial. The electronically conductive support structure is generallyporous to allow fluid (air) flow and either catalytic or treated with acatalyst to catalyze the reduction of the cathode active material. Anaqueous electrolyte with suitable ionic conductivity or ionomer is alsoin contact with the electronically conductive support structure to allowion transport within the electronically conductive support structure tocomplete the redox reaction.

The air cathode system includes an electronically conductive component(for example, a porous electronic conductor), an ionically conductivecomponent with at least an aqueous constituent, and air as anelectrochemically active component. It may be any suitable airelectrode, including those conventionally used in metal (e.g., Zn)/airbatteries or low temperature (e.g., PEM) fuel cells. Air cathodes usedin metal/air batteries, in particular in Zn/air batteries, are describedin many sources including “Handbook of Batteries” (Linden and T. B.Reddy, McGraw-Hill, NY, Third Edition) and are usually composed ofseveral layers including an air diffusion membrane, a hydrophobic Teflonlayer, a catalyst layer, and a metal electronically conductivecomponent/current collector, such as a Ni screen. The catalyst layeralso includes an ionically conductive component/electrolyte that may beaqueous and/or ionomeric. A typical aqueous electrolyte is composed ofKOH dissolved in water. A typical ionomeric electrolyte is composed of ahydrated (water) Li ion conductive polymer such as a per-fluoro-sulfonicacid polymer film (e.g., du Pont NAFION). The air diffusion membraneadjusts the air (oxygen) flow. The hydrophobic layer preventspenetration of the cell's electrolyte into the air-diffusion membrane.This layer usually contains carbon and Teflon particles. The catalystlayer usually contains a high surface area carbon and a catalyst foracceleration of reduction of oxygen gas. Metal oxides, for example MnO₂,are used as the catalysts for oxygen reduction in most of the commercialcathodes. Alternative catalysts include metal macrocycles such as cobaltphthalocyanine, and highly dispersed precious metals such at platinumand platinum/ruthenium alloys. Since the air electrode structure ischemically isolated from the active metal electrode, the chemicalcomposition of the air electrode is not constrained by potentialreactivity with the anode active material. This can allow for the designof higher performance air electrodes using materials that would normallyattack unprotected metal electrodes.

Another type of active metal/aqueous battery cell incorporating aprotected anode and a cathode system with an aqueous component inaccordance with the present invention is a lithium (or other activemetal)/metal hydride battery. For example, lithium anodes protected witha non-aqueous interlayer architecture as described herein can bedischarged and charged in aqueous solutions suitable as electrolytes ina lithium/metal hydride battery. Suitable electrolytes provide a sourceor protons. Examples include aqueous solutions of halide acids or acidicsalts, including chloride or bromide acids or salts, for example HCl,HBr, NH₄Cl or NH₄Br.

In addition to the aqueous, air, etc., systems noted above, improvedperformance can be obtained with cathode systems incorporatingconventional Li-ion battery cathodes and electrolytes, such as metaloxide cathodes (e.g., Li_(x)Co₂, Li_(x)NiO₂, Li_(x)Mn₂O₄ and LiFePO₄)and the binary, ternary or multicomponent mixtures of alkyl carbonatesor their mixtures with ethers as solvents for a Li metal salt (e.g.,LiPF₆, LiAsF₆ or LiBF₄); or Li metal battery cathodes (e.g., elementalsulfur or polysulfides) and electrolytes composed of organic carbonates,ethers, glymes, lactones, sulfones, sulfolane, and combinations thereof,such as EC, PC, DEC, DMC, EMC, 1,2-DME, THF, 2MeTHF, and combinationsthereof, as described, for example, in U.S. Pat. No. 6,376,123,incorporated herein by reference.

Moreover, the catholyte solution can be composed of only low viscositysolvents, such as ethers like 1,2-dimethoxy ethane (DME),tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxolane (DIOX),4-methyldioxolane (4-MeDIOX) or organic carbonates likedimethylcarbonate (DMC), ethylmethylcarbonate (EMC), diethylcarbonate(DEC), or their mixtures. Also, super low viscosity ester solvents orco-solvents such as methyl formate and methyl acetate, which are veryreactive to unprotected Li, can be used. As is known to those skilled inthe art, ionic conductivity and diffusion rates are inverselyproportional to viscosity such that all other things being equal,battery performance improves as the viscosity of the solvent decreases.The use of such catholyte solvent systems significantly improves batteryperformance, in particular discharge and charge characteristics at lowtemperatures.

Ionic liquids may also be used in catholytes of the present invention.Ionic liquids are organic salts with melting points under 100 degrees,often even lower than room temperature. The most common ionic liquidsare imidazolium and pyridinium derivatives, but also phosphonium ortetralkylammonium compounds are also known. Ionic liquids have thedesirable attributes of high ionic conductivity, high thermal stability,no measurable vapor pressure, and non-flammability. Representative ionicliquids are 1-Ethyl-3-methylimidazolium tosylate (EMIM-Ts),1-Butyl-3-methylimidazolium octyl sulfate (BMIM-OctSO4),1-Ethyl-3-methylimidazolium hexafluorophosphate, and1-Hexyl-3-methylimidazoliumtetrafluoroborate. Although there has beensubstantial interest in ionic liquids for electrochemical applicationssuch as capacitors and batteries, they are unstable to metallic lithiumand lithiated carbon. However, protected lithium anodes as described inthis invention are isolated from direct chemical reaction, andconsequently lithium metal batteries using ionic liquids are possible asan embodiment of the present invention. Such batteries should beparticularly stable at elevated temperatures.

Safety Additives

As a safety measure, the non-aqueous interlayer architecture canincorporate a gelling/polymerizing agent that, when in contact with thereactive electrolyte (for example water), leads to the formation of animpervious polymer on the anode (e.g., lithium) surface. This safetymeasure is used for the case where the substantially impervious layer ofthe protective architecture (e.g., a glass or glass-ceramic membrane)cracks or otherwise breaks down and allows the aggressive catholyte toenter and approach the lithium electrode raising the possibility of aviolent reaction between the Li anode and aqueous catholyte.

Such a reaction can be prevented by providing in the anolyte a monomerfor a polymer that is insoluble or minimally soluble in water, forexample dioxolane (Diox) (for example, in an amount of about 5-20% byvolume) and in the catholyte a polymerization initiator for the monomer,for example, a protonic acid. A Diox based anolyte may be composed oforganic carbonates (EC, PC, DEC, DMC, EMC), ethers (1, 2-DME, THF,2MeTHF, 1,3-dioxolane and others) and their mixtures. Anolyte comprisingdioxolane as a main solvent (e.g., 50-100% by volume) and Li salt, inparticular, LiAsF₆, LiBF₄, LiSO₃CF₃, LiN(SO₂C₂F)₂, is especiallyattractive. Diox is a good passivating agent for Li surface, and goodcycling data for Li metal has been achieved in the Diox basedelectrolytes (see, e.g., U.S. Pat. No. 5,506,068). In addition to itscompatibility with Li metal, Diox in combination with above-mentionedionic salts forms highly conductive electrolytes. A correspondingaqueous catholyte contains a polymerization initiator for Diox thatproduces a Diox polymerization product (polydioxolane) that is not or isonly minimally soluble in water.

If the membrane breaks down, the catholyte containing the dissolvedinitiator comes in direct contact with the Diox based anolyte, andpolymerization of Diox occurs next to the Li anode surface.Polydioxolane, which is a product of Diox polymerization, has highresistance, so the cell shuts down. In addition, the Polydioxolane layerformed serves as a barrier preventing reaction between the Li surfaceand the aqueous catholyte. Diox can be polymerized with protonic acidsdissolved in the catholyte. Also, the water soluble Lewis acids, inparticular benbenzoyl cation, can serve this purpose.

Thus, improvement in cyclability and safety is achieved by the use of adioxolane (Diox) based anolyte and a catholyte containing apolymerization initiator for Diox.

Active Metal Ion and Alloy Anodes

The invention pertains to batteries and other electrochemical structureshaving anodes composed of active metals, as described above. A preferredactive metal electrode is composed of lithium (Li). Suitable anolytesfor these structures and cells are described above.

The invention also pertains to electrochemical structures having activemetal ion (e.g., lithium-carbon) or active metal alloy (e.g., Li—Sn)anodes. Some structures may initially have uncharged active metal ionintercalation materials (e.g., carbon) or alloying metals (e.g., tin(Sn)) that are subsequently charged with active metal or active metalions. While the invention may be applicable to a variety of activemetals, it is described herein primarily with reference to lithium, asan example.

Carbon materials commonly used in conventional Li-ion cells, inparticular petroleum coke and mesocarbon microbead carbons, can be usedas anode materials in Li-ion aqueous battery cells. Lithium alloyscomprising one or several of the metals selected from the groupincluding Ca, Mg, Sn, Ag, Zn, Bi, Al, Cd, Ga, In and Sb, preferably Al,Sn or Si, can also be used as anode materials for such a battery. In oneparticular embodiment the anode comprises Li, Cu and Sn.

Anolyte for such structures can incorporate supporting salts, forexample, LiPF₆, LiBF₄, LiAsF₆, LiClO₄, LiSO₃CF₃, LiN(CF₃SO₂)₂ orLiN(SO₂C₂F₅)₂ dissolved in binary or ternary mixtures of non-aqueoussolvents, for example, EC, PC, DEC, DMC, EMC, MA, MF, commonly used inconventional Li-ion cells. Gel-polymer electrolytes, for instanceelectrolytes comprising one of the above mentioned salts, a polymericbinder, such as PVdF, PVdF-HFP copolymer, PAN or PEO, and a plasticizer(solvent) such as EC, PC, DEC, DMC, EMC, THF, 2MeTHF, 1,2-DME and theirmixtures, also can be used.

For batteries using these anodes, a suitable cathode structure may beadded to the electrochemical structure on the other side of theprotective architecture. The architecture enables Li-ion type cellsusing a number of exotic cathodes such as air, water, metal hydrides ormetal oxides. For Li-ion aqueous battery cells, for example, aqueouscatholyte can be basic, acidic or neutral and contains Li cations. Oneexample of a suitable aqueous catholyte is 2 M LiCl, 1 M HCl.

During the first charge of the battery with lithium-carbon lithium alloyanode, Li cations are transported from the catholyte through theprotective architecture (including the anolyte) to the anode surfacewhere the intercalation process takes place as in conventional Li-ioncells. In one embodiment, the anode is chemically or electrochemicallylithiated ex-situ before cell assembly.

Cell Designs

Electrochemical structures and battery cells in accordance with thepresent invention may have any suitable geometry. For example, planargeometries may be achieved by stacking planar layers of the variouscomponents of the structures or cells (anode, interlayer, cathode, etc.)according to known battery cell fabrication techniques that are readilyadaptable to the present invention given the description of thestructure or cell components provided herein. These stacked layers maybe configured as prismatic structures or cells.

Alternatively, the use of tubular glass or glass-ceramic electrolyteswith a non-aqueous interlayer architecture allows for the constructionof high surface area anodes with low seal area. As opposed to flat-platedesign where the seal length increases with cell surface area, tubularconstruction utilizes an end seal where the length of the tube can beincreased to boost surface area while the seal area is invariant. Thisallows for the construction of high surface area Li/water and Li/aircells that should have correspondingly high power density.

The use of a non-aqueous interlayer architecture in accordance with thepresent invention facilitates construction. An open-ended (with a seal)or close-ended glass or glass-ceramic (i.e., substantially imperviousactive metal ion conductive solid electrolyte) tube is partially filledwith a non-aqueous organic electrolyte (anolyte or transfer electrolyte)as described above, for example such as is typically used in lithiumprimary batteries A lithium metal rod surrounded by some type ofphysical separator (e.g., a semi-permeable polymer film such as Celgard,Tonin, polypropylene mesh, etc.) having a current collector is insertedinto the tube. A simple epoxy seal, glass-to-metal seal, or otherappropriate seal is used to physically isolate the lithium from theenvironment.

The protected anode can then be inserted in a cylindrical air electrodeto make a cylindrical cell, as shown in FIG. 3A. Or an array of anodesmight be inserted into a prismatic air electrode, as shown in FIG. 3B.

This technology can also be used to build Li/water, Li/metal hydride orLi/metal oxide cells by substituting the air electrode with suitableaqueous, metal hydride or metal oxide cathode systems, as describedherein above.

In addition to the use of lithium metal rods or wires (in capillarytubes), this invention can also be used to isolate a rechargeableLiC_(x) anode from aqueous or otherwise corrosive environments. In thiscase, appropriate anolyte (transfer electrolyte) solvents are used inthe tubular anode to form a passive film on the lithiated carbonelectrode. This would allow the construction of high surface area Li-iontype cells using a number of exotic cathodes such as air, water, metalhydrides or metal oxides, for example, as shown in FIG. 3C.

EXAMPLES

The following examples provide details illustrating advantageousproperties of Li metal and Li-ion aqueous battery cells in accordancewith the present invention. These examples are provided to exemplify andmore clearly illustrate aspects of the present invention and in no wayintended to be limiting.

Example 1: Li/Seawater Cell

A series of experiments was performed in which the commercial ionicallyconductive glass-ceramic from OHARA Corporation was used as a membraneseparating aqueous catholyte and non-aqueous anolyte. The cell structurewas Li/non-aqueous electrolyte/glass-ceramic/aqueous electrolyte/Pt. Alithium foil from Chemetall Foote Corporation with thickness of 125microns was used as the anode. The GLASS-CERAMIC plates were in therange of 0.3 to 0.48 mm in thickness. The GLASS-CERAMIC plate was fittedinto an electrochemical cell by use of two o-rings such that theGLASS-CERAMIC plate was exposed to an aqueous environment from one sideand a non-aqueous environment from the other side. In this case, theaqueous electrolyte comprised an artificial seawater prepared with 35ppt of “Instant Ocean” from Aquarium Systems, Inc. The conductivity ofthe seawater was determined to be 4.5 10-2 S/cm. A microporous Celgardseparator placed on the other side of the GLASS-CERAMIC was filled withnon-aqueous electrolyte comprised of 1 M LiPF₆ dissolved in propylenecarbonate. The loading volume of the nonaqueous electrolyte was 0.25 mlper 1 cm² of Li electrode surface. A platinum counter electrodecompletely immersed in the sea water catholyte was used to facilitatehydrogen reduction when the battery circuit was completed. An Ag/AgClreference electrode was used to control potential of the Li anode in thecell. Measured values were recalculated into potentials in the StandardHydrogen Electrode (SHE) scale. An open circuit potential (OCP) of 3.05volts corresponding closely to the thermodynamic potential differencebetween Li/Li⁺ and H₂/H⁺ in water was observed (FIG. 4). When thecircuit was closed, hydrogen evolution was seen immediately at the Ptelectrode, which was indicative of the anode and cathode electrodereactions in the cell, 2Li=2Li+2e⁻ and 2H⁺+2e⁻=H₂. The potential-timecurve for Li anodic dissolution at a discharge rate of 0.3 mA/cm² ispresented in FIG. 2. The results indicate an operational cell with astable discharge voltage. It should be emphasized that in allexperiments using a Li anode in direct contact with seawater utilizationof Li was very poor, and such batteries could not be used at all at lowand moderate current densities similar to those used in this example dueto the extremely high rate of Li corrosion in seawater (over 19 A/cm²).

Example 2: Li/Air Cell

The cell structure was similar to that in the previous example, butinstead of a Pt electrode completely immersed in the electrolyte, thisexperimental cell had an air electrode made for commercial Zn/Airbatteries. An aqueous electrolyte used was 1 M LiOH. A Li anode and anon-aqueous electrolyte were the same as described in the previousexample.

An open circuit potential of 3.2 V was observed for this cell. FIG. 5shows discharge voltage-time curve at discharge rate of 0.3 mA/cm². Thecell exhibited discharge voltage of 2.8-2.9 V. for more than 14 hrs.This result shows that good performance can be achieved for Li/air cellswith solid electrolyte membrane separating aqueous catholyte andnon-aqueous anolyte.

Example 3: Li-ion Cell

In these experiments the commercial ionically conductive glass-ceramicfrom OHARA Corporation was used as a membrane separating aqueouscatholyte and non-aqueous anolyte. The cell structure wascarbon/non-aqueous electrolyte/glass-ceramic plate/aqueouselectrolyte/Pt. A commercial carbon electrode on copper substratecomprising a synthetic graphite similar to carbon electrodes commonlyused in lithium-ion batteries was used as the anode. The thickness ofthe glass-ceramic plate was 0.3 mm. The glass-ceramic plate was fittedinto an electrochemical cell by use of two o-rings such that theglass-ceramic plate was exposed to an aqueous environment from one sideand a non-aqueous environment from the other side. The aqueouselectrolyte comprised 2 M LiCl and 1 M HCl. Two layers of microporousCelgard separator placed on the other side of the glass-ceramic werefilled with non-aqueous electrolyte comprised of 1 M LiPF₆ dissolved inthe mixture of ethylene carbonate and dimethyl carbonate (1:1 byvolume). A lithium wire reference electrode was placed between twolayers of Celgard separator in order to control the potential of thecarbon anode during cycling. A platinum mesh completely immersed in the2 M LiCl, 1 M HC solution was used as the cell cathode. An Ag/AgClreference electrode placed in the aqueous electrolyte was used tocontrol potential of the carbon electrode and voltage drop across theGLASS-CERAMIC plate, as well as potential of the Pt cathode duringcycling. An open circuit voltage (OCV) around 1 volt was observed forthis cell. The voltage difference of 3.2 volts between Li referenceelectrode and Ag/AgCl reference electrode closely corresponding to thethermodynamical value was observed. The cell was charged at 0.1 mA/cm2until the carbon electrode potential reached 5 mV vs. Li referenceelectrode, and then at 0.05 mA/cm² using the same cutoff potential. Thedischarge rate was 0.1 mA/cm², and discharge cutoff potential for thecarbon anode was 1.8 V vs. Li reference electrode. The data in FIG. 6show that the cell with intercalation carbon anode and aqueouselectrolyte containing Li cations can work reversibly. This is the firstknown example where aqueous solution has been used in Li-ion cellinstead of solid lithiated oxide cathode as a source of Li ions forcharging of the carbon anode.

Alternative Embodiment—Li/Water Battery and Hydrogen Generator for FuelCell

The use of protective architecture on active metal electrodes inaccordance with the present invention allows the construction of activemetal/water batteries that have negligible corrosion currents, describedabove. The Li/water battery has a very high theoretical energy densityof 8450 Wh/kg. The cell reaction is Li+H₂O═LiOH+½ H₂. Although thehydrogen produced by the cell reaction is typically lost, in thisembodiment of the present invention it is used to provide fuel for anambient temperature fuel cell. The hydrogen produced can be either feddirectly into the fuel cell or it can be used to recharge a metalhydride alloy for later use in a fuel cell. At least one company,Millenium Cell, makes use of the reaction of sodium borohydride withwater to produce hydrogen. However, this reaction requires the use of acatalyst, and the energy produced from the chemical reaction of NaBH₄and water is lost as heat.

NaBH₄+2 H₂O->4H₂+NaBO₂

When combined with the fuel cell reaction, H₂+O₂═H₂O, the full cellreaction is believed to be:

NaBH₄+2O₂->2H₂O+NaBO₂

The energy density for this system can be calculated from the equivalentweight of the NaBH₄ reactant (38/4=9.5 grams/equiv.). The gravimetriccapacity of NaBH₄ is 2820 mAh/g; since the voltage of the cell is about1, the specific energy of this system is 2820 Wh/kg. If one calculatesthe energy density based on the end product NaBO₂, the energy density islower, about 1620 Wh/kg.

In the case of the Li/water cell, the hydrogen generation proceeds by anelectrochemical reaction believed described by:

Li+H₂O=LiOH+½H₂

In this case, the energy of the chemical reaction is converted toelectrical energy in a 3 volt cell, followed by conversion of thehydrogen to water in a fuel cell, giving an overall cell reactionbelieved described by:

Li+½H₂O+¼O₂═LiOH

where all the chemical energy is theoretically converted to electricalenergy. The energy density based on the lithium anode is 3830 mAh/g at acell potential of about 3 volts which is 11,500 Wh/kg (4 times higherthan NaBH₄). If one includes the weight of water needed for thereaction, the energy density is then 5030 Wh/kg. If the energy densityis based on the weight of the discharge product, LiOH, it is then 3500Wh/kg, or twice the energy density of the NaBO₂ system. This can becompared to previous concepts where the reaction of lithium metal withwater to produce hydrogen has also been considered. In that scenario theenergy density is lowered by a factor of three, since the majority ofthe energy in the Li/H₂O reaction is wasted as heat, and the energydensity is based on a cell potential for the H₂/O₂ couple (as opposed to3 for Li/H₂O) which in practice is less than one. In this embodiment ofthe present invention, illustrated in FIG. 7, the production of hydrogencan also be carefully controlled by load across the Li/water battery,the Li/water battery has a long shelf life due to the protectivemembrane, and the hydrogen leaving the cell is already humidified foruse in the H₂/air fuel cell.

CONCLUSION

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theinvention. In particular, while the invention is primarily describedwith reference to a lithium metal, alloy or intercalation anode, theanode may also be composed of any active metal, in particular, otheralkali metals, such as sodium. It should be noted that there are manyalternative ways of implementing both the process and compositions ofthe present invention. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein.

All references cited herein are incorporated by reference for allpurposes.

1-20. (canceled)
 21. A method of making a battery cell, comprising:providing a protected lithium metal electrode comprising a lithium anodeand a protective architecture, the protective architecture comprising afirst lithium ion conducting separator layer and a second lithium ionconducting layer, wherein the first layer further comprises a lithiumion conducting anolyte, and the second layer is a substantiallyimpervious layer that prevents the lithium anode from deleteriousreaction in direct contact with seawater; contacting the substantiallyimpervious second layer of the protected lithium metal electrode withseawater to provide a cathode for the cell.
 22. The method of claim 21wherein the lithium anode is lithium metal.
 23. The method of claim 21wherein the lithium anode comprises intercalating carbon.
 24. The methodof claim 21 wherein the lithium anode comprises a lithium alloyingmaterial.
 25. The method of claim 24 wherein the lithium alloyingmaterial is silicon or tin.
 26. The method of claim 21 wherein theanolyte is a liquid electrolyte.
 27. The method of claim 21 wherein theanolyte is a gel electrolyte.
 28. The method of claim 21 wherein theanolyte is a polymer electrolyte.
 29. The method of claim 21 wherein thefirst separator layer further comprises glass or ceramic particles. 30.The method of claim 29 wherein the glass or ceramic particles gettershorting dendrites.
 31. The method of claim 21 wherein the lithium ionconducting substantially impervious second layer directly contacts theseawater of the cathode.
 32. The method of claim 21 wherein thesubstantially impervious second material layer is a tape cast layer. 33.The method of claim 32 wherein the tape cast layer comprises a garnetlithium ion conductor.
 34. The method of claim 21 wherein the secondmaterial layer comprises a garnet lithium ion conductor.
 35. The methodof claim 21 wherein the second material layer comprises a ceramiclithium ion conductor comprising lithium titanium phosphate.
 36. Themethod of claim 33 wherein the second material layer comprises a ceramiclithium ion conductor comprising lithium titanium phosphate.
 37. Themethod of claim 21 wherein the contacting the substantially impervioussecond layer of the protected lithium metal electrode with seawater toprovide a cathode for the cell comprises immersing the protected lithiumelectrode in seawater.